1. Field of the Disclosure
This disclosure relates to a barrier panel as well as a three dimensional image display device including a barrier panel.
2. Description of the Related Art
A variety of methods for implementing a three dimensional image display device using binocular parallax have been proposed in a variety of ways for a long time. One representative method places one of a lenticular lens and a parallax barrier at a fixed distance away from a two dimensional image panel and provides the two eyes of the viewer with images different from each other, thereby allowing the viewer to have a sense of solidity.
A three dimensional image display device including the lenticular lens provides left and right images in a striped shape on a focus surface of each lens of a lenticular lens sheet, which is called a lenticular screen, and makes the left and right images separate from each other by the lenses according to a directivity of the lenticular sheet, so that a viewer can view a three dimensional image without a pair of glasses. The width of a single lenticular lens depends on that of each pixel on the display device. More specifically, the width of a single lenticular lens is set to include two pixels which each correspond to left and right pixels. In this case, a lens effect forces not only a left side pixel of the lenticular lens to be viewed just from the right eye of the viewer but also a right side pixel of the lenticular lens to be viewed just from the left eye of the viewer. In accordance therewith, it becomes possible to separate the left and right images from each other.
Another three dimensional image display device using the parallax barrier arranges vertical slits, which are formed in striped shapes and used to transmit or intercept light, in a fixed interval and enables left and right images to be alternately provided in one of the front or rear directions of the vertical slits at a fixed distance. In accordance therewith, the left and right images are viewed from a fixed viewing point through the vertical slits in such a manner as to be accurately and geometric-optically separate from each other and to make a viewer to have a sense of solidity. In other words, this three dimensional image display device disposes a parallax barrier's optic-plate, which includes striped patterns and functions as special glasses, in the front of a monitor screen so that a viewer can recognize a three dimensional image without the special glasses.
FIG. 1 is a diagram showing a three dimensional image display device which is implemented using a parallax barrier.
Referring to FIG. 1, a three dimensional image display device of the related art includes a liquid crystal panel 11 and a parallax barrier 12 which is disposed in the rear direction of the liquid crystal panel 11 at a fixed distance. The liquid crystal panel 11 is formed to allow left and right image stripes L and R to be alternately arranged with a pixel pitch “P”. The parallax barrier 12 is formed to allow transparent and opaque portions 12a and 12b to be not only alternately arranged with each other but also repeated at every barrier pitch “q”.
Such a three dimensional image display device enables light from a light source (not shown) to sequentially pass through the transparent portion 12a and the liquid crystal panel 11 and reach both eyes LE and RE of a viewer. More specifically, the lights passed through the right image stripes R reach the right eye RE of the viewer, and the lights passed through the left image stripes L reach the left eye LE of the viewer. In this manner, the left and right images L and R are recognized by both eyes of the viewer, respectively, so that two different two-dimensional-image informations can be input to the viewer. Therefore, the viewer can obtain image information with having a sense of solidity (that is, three dimensional image information).
If the opaque portions 12b of the parallax barrier 12 are processed to become transparent, light emitted from the light source sequentially passes through the parallax barrier 12 and the liquid crystal panel 11 and reaches the viewer. In accordance therewith, the three dimensional image display device can display a two dimension image similar to the ordinarily two-dimensional image display device. In other words, the three dimensional image display device can selectively display the two and three dimensional images by controlling the opaque portions 12b of the parallax barrier 12.
The above-mentioned three dimensional image display device must satisfy conditions necessary to give a viewer a sense of solidity. The necessary conditions can be written as the following equation 1.
                              d          =                                                    (                                                      2                    ⁢                    n                                    +                  1                                )                            ⁢                              P                ⁡                                  (                                      D                    +                    d                                    )                                                      S                          ,                            [                  Equation          ⁢                                          ⁢          1                ]                                q        =                              2            ⁢                          P              ⁡                              (                                  D                  +                  d                                )                                              D                                                
In the equation 1, “n” is a positive integer, “S” is the distance between both eyes of the viewer, and “D” is the shortest distance between the liquid crystal panel and the eyes of a viewer. Also, “d” is the shortest distance between the parallax barrier and the liquid crystal panel, “q” is a barrier pitch of the parallax barrier, and “P” is a pixel pitch of the liquid crystal panel.
FIG. 2 is a diagram showing a parallax barrier of the three dimensional image display device according to the related art.
Referring to FIG. 2, the related art parallax barrier used in the three dimensional image device is schematically shown. The related art parallax barrier includes: an upper substrate on which a common electrode 21 is formed; a lower substrate, opposite to the upper substrate, provided with striped electrodes 22 which are arranged in a fixed barrier pitch; and a power supply unit 23 configured to control the transparent and opaque statuses of a liquid crystal layer between the upper and lower substrates by inducting a re-alignment of the liquid crystal layer. The power supply unit 23 either applies a voltage between the common electrode 21 and the striped electrodes 22 or intercepts the voltage applied between the common electrode 21 and the striped electrodes 22, so that portions of the liquid crystal layer corresponding to the striped electrodes 22 become the transparent or opaque status. In accordance therewith, a three dimensional image or a two dimensional image is displayed.
FIGS. 3 and 4 are diagrams for illustrating problems of a three dimensional image display device using a related art parallax barrier.
As shown in FIG. 3, the three dimensional image display device allows not only left striped images to be viewed from the left eye of a viewer but also right striped images to be viewed from the right eye of the viewer. In this case, the left striped images and the right striped images are synthesized so that the viewer has a sense of solidity for the synthesized image. Meanwhile, if both eyes of the viewer are moved from a position of “R and L” to another position of “R′ and L′” as shown in FIG. 4, the striped images are partially shielded. Due to this, a three dimensional image can not be realized. In other word, when both eyes of the viewer are moved from one position of “R and L” to another position of “R′ and L′”, the parallax barrier must be shifted by a distance of “W” in order to continuously realize the three dimensional image.
However, the parallax barrier included in a three dimensional image display device of the related art must be fixed in position. As such, a visible angular range allowing the viewer to view a three dimensional image must be limited within left and right angles of about 5°.